About Lapse Rate

As a hypothetical parcel of air cools as it rises in the atmosphere and warms as it descends in the atmosphere. This cooling and warming of the air is known as the lapse rate. There are two primary types of lapse rate - the dry adiabatic lapse rate and the wet or saturated adiabatic lapse rate.

If you're having trouble thinking about a parcel of air rising, think of a invisible balloon of air rising. As it rises, it cools as it expands. If it begins to descend it will compress and the temperature will increase.